Method and device for transferring extrusion-molded articles

ABSTRACT

Buffer means  20 Z consisting of an expansion conveyor  20   a , inverted conveyor  20   b  and expansion conveyor  20   c  is interposed between the conveyors  24  and  25  of a conveying unit  20  so that when a trouble occurs in a receiving unit  30 , the expansion conveyors  20   a  and  20   c  of the buffer means  20 Z are expanded to extend the conveying line, and the extruder revolution R and the conveyor speed V are changed to reduce the conveying speed not to carry the extruded treads  1  to the receiving unit  30 . When the above trouble is solved, the conveying line of the buffer means  20 Z is made the shortest, and the extruder revolution R and the conveyor speed V are changed to increase the conveying speed so as to carry the buffered extruded treads to the receiving unit  30.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of conveying extrusion moldedproducts which are continuously extruded, such as tire treads, and to adevice for use in the method.

2. Description of the Prior Art

In an extruding/conveying line of the prior art, the above treads aredelivered from an extruder at an extrusion speed which is determinedaccording to the size of the extruded treads and carried to a receivingunit at the same speed as the above delivery speed by a plurality ofconveyors.

However, since the conveying speed is fixed in the above prior artmethod, when a trouble occurs in the receiving unit, for example, theextruding/conveying line must be suspended and also work for processingafter suspension before the resumption of extrusion takes a long time.Further, a trouble occurs in the end portion of an extrusion moldedproduct during the time from the resumption of extrusion to theproduction of a quality product.

When a tread is removed before the receiving unit or when a tread iscarried to a place other than the receiving unit, a quality productcannot be received by a predetermined method, whereby it is regarded asan inferior product.

It is an object of the present invention which has been made in view ofthe above problem to provide a method of conveying extrusion moldedproducts, which prevents extrusion molded products from being carried toa receiving unit without suspending a conveying line for a predeterminedtime even when a trouble occurs in the receiving unit as well as adevice for use in the method.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda method of conveying extrusion molded products from a material feedunit to a receiving unit by a plurality of conveyors, comprisinginterposing at least one expansion conveyor between conveyors out of theconveyors to expand or contract the expansion conveyor in order toadjust the conveying speed of the extrusion molded products. Thereby,even when a trouble occurs in the receiving unit, the above expansionconveyor is expanded to extend the conveying line so as to buffer theabove extrusion molded products while they are carried. Therefore, theextrusion molded products are not carried to the receiving unit withoutsuspending the conveying line for a predetermined time. After thetrouble is solved, the above expansion conveyor is contracted to shortenthe conveying line and the extrusion molded products in stock can becarried to the receiving unit swiftly. Therefore, productivity can beimproved.

According to a second aspect of the present invention, there is provideda method of conveying extrusion molded products, wherein the conveyorspeed of the conveyors can be changed to several levels. Thereby, whenthe above trouble occurs, the conveying speed is reduced to extend thetime elapsed before the buffer becomes full and after the trouble issolved, the conveying speed is increased to return the conveying line tonormal operation swiftly.

According to a third aspect of the present invention, there is provideda method of conveying extrusion molded products, wherein the deliveryspeed of the material feed unit is controlled according to a change inthe conveyor speed of the conveyors. Thereby, the extrusion moldedproducts can be carried smoothly.

According to a fourth aspect of the present invention, there is provideda method of conveying extrusion molded products, wherein when thematerial feed unit has a plurality of extruders, the speed of eachextruder is controlled according to a change in the conveyor speed ofthe conveyors.

According to a fifth aspect of the present invention, there is provideda method of conveying extrusion molded products, wherein a responsedelay of the delivery speed of the material feed unit to the conveyorspeed of the conveyors and the attenuation time are obtained in advanceand when the conveyor speed of the conveyors is changed, the targetvalue of the delivery speed is set based on the response delay and theattenuation time.

According to a sixth aspect of the present invention, there is provideda method of conveying extrusion molded products, wherein the targetvalue of conveying speed is set according to the throughput of thereceiving unit.

According to a seventh aspect of the present invention, there isprovided a device for conveying extrusion molded products, having aplurality of conveyors to carry extrusion molded products from amaterial feed unit to a receiving unit, wherein at least one expansionconveyor is interposed between conveyors out of the plurality ofconveyors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the constitution of a device forcarrying extrusion molded products according to a preferred embodimentof the present invention;

FIG. 2 is a flow chart showing a method of carrying extrusion moldedproducts according to the preferred embodiment of the present invention;

FIG. 3 is a diagram showing a speed table for conveyors and extruders;

FIG. 4 is a diagram showing a response delay of the delivery speed of atread extruder to the conveying speed of the conveyors and attenuationtime; and

FIG. 5 is a diagram showing a control example of the delivery speed ofthe extruder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be describedhereinbelow with reference to the drawings.

FIG. 1 is a schematic diagram showing the constitution of a device forconveying extrusion molded products according to the present invention.In FIG. 1, reference numeral 10 denotes a tread extruder (to be referredto as “extruder” hereinafter) which is a material feed unit fordelivering extrusion molded products at a predetermined delivery speed,20 a conveying unit for carrying belt-like extruded treads 1 deliveredfrom the extruder 10, which comprises a plurality of conveyors 21 to 27and buffer means 20Z interposed between an inverted conveyor 24 and aninclined conveyor 25 and consisting of an expansion conveyor 20 a,inverted conveyor 20 b and expansion conveyor 20 c, and 30 a receivingunit for receiving the carried extruded treads 1, which is located on adownstream side of the last conveyor 27 of the above conveying unit 20.

Reference numeral 41 denotes a speed control CPU for controlling anextruder revolution R corresponding to the delivery speed of theextruder 10 and the conveyor speed V of the conveyors 21 to 27, 20 a, 20b and 20 c, 42 an expansion control CPU for expanding and contractingthe expansion conveyors 20 a and 20 c of the buffer means 20Z and movingthe position of the inverted conveyor 20 b according to the expansion orcontraction of the above expansion conveyors 20 a and 20 c, and 43 areception control CPU for monitoring and controlling the tread receivingand processing states of the receiving unit 30.

A description is subsequently given of the operation of the device forconveying extrusion molded products of the present invention withreference to the flow chart of FIG. 2.

In step S10, the belt-like extruded treads 1 are delivered from theextruder 10 to the conveying unit 20 at a predetermined extruder speed(extruder revolution) R₀ and carried to the receiving unit 30 at aconveyor speed V₀ corresponding to the above extruder revolution R₀. Thecontrol of the above extruder revolution R₀ and the conveyor speed V₀ iscarried out by the speed control CPU 41.

The reception control CPU 43 monitors whether there is a trouble in thetread receiving and processing states of the receiving unit 30 (stepS11). When there is no trouble, the above normal operation is continued.When a trouble occurs in the receiving unit 30, the above troubleinformation is sent to the expansion control CPU 42 and the speedcontrol CPU 41 from the above reception control CPU 43 to enable theexpansion control CPU 42 to expand the expansion conveyors 20 a and 20 cof the buffer means 20Z and move the inverted conveyor 20 b inaccordance with the expansion of the above expansion conveyors 20 a and20 b so as to extend the conveying line and to enable the speed controlCPU 41 to change the extruder revolution R and the speed V of theconveyors 21-27, 20 a, 20 b and 20 c of the conveying unit 20 to R_(L)(<R₀) and V_(L) (<V₀), respectively, so as to reduce the conveyingspeed, thereby buffering the extruded treads 1 not to carry them to thereceiving unit 30 (step S12).

FIG. 3 is a speed table showing the extruder speed (extruder revolution)R and the conveyor speed V controlled by the speed control CPU 41. Inthis embodiment, the conveyor speed V is set to several levels (theconveyor speed V is set to a range of 0.5 to 20 m/min in increments of0.1 m/min) and the delivery speed of the extruder 10 is controlledaccording to a change in the conveyor speed V of the above conveyors.When there are a plurality of extruders 10 (extruder #1 and extruder #2in this embodiment), the revolution R of each extruder is changedaccording to the above conveyor speed V.

When the speed of the extruder 10 (extruder revolution R) is changedaccording to the above conveyor speed, the amount of extrusion becomesinsufficient. Therefore, as shown in FIG. 4, a response delay of thedelivery speed of the extruder 10 to the conveyor speed of the conveyorsand the attenuation time are obtained in advance and the target value ofthe above delivery speed is set based on the above response delay andthe attenuation time when the conveyor speed of the conveyors ischanged. Stated more specifically, as shown in FIG. 5, the target valueof delivery speed of the extruder 10 is set to a value obtained byadding the response delay “r” to the above conveyor speed. How fast (inseconds) the delivery speed of the extruder 10 is reduced to a targetvalue is determined by the attenuation time “T” as a parameter for eachextruder 10. Thereby, even when the speed is variable, predeterminedquality products can be obtained.

The conveyor speed V_(L) and the extruder revolution R_(L) which arechanged to reduce the delivery speed may be determined according to thetrouble information sent from the reception control CPU 43 to the speedcontrol CPU 41 or may be reduced stepwise every a predetermined time.

Thereby, when a trouble occurs in the receiving unit 30, it can besolved without carrying the extruded treads 1 to the receiving unit 30until the above buffer means 20 becomes full, thereby making it possibleto avoid the manufacture of inferior products.

During the above low-speed operation, the reception control CPU 43monitors whether the trouble in the receiving unit 30 is solved or not(steps S13 and S14). When the trouble is not solved, low-speed operationis continued. If the trouble is not solved within a predetermined timeduring which buffering is possible, the delivery of the extruded treads1 is suspended (step S15).

When the trouble is solved, the routine proceeds to step S16 whereinformation on the solution of the trouble is sent to the expansioncontrol CPU 42 and the speed control CPU 41 from the reception controlCPU 43 so that the expansion control CPU 43 can contract the expansionconveyors 20 a and 20 c of the buffer means 20Z to the full, therebyminimizing the length of the conveying line and that the speed controlCPU 41 changes the extruder revolution R and the conveyor speed V of theconveyors 21-27, 20 a, 20 b and 20 c of the conveying unit 20 to R_(H)(>R₀) and V_(H) (>V₀), respectively, to increase the conveying speed andcarry the buffered extruded treads 1 to the receiving unit 30.

To shift to the high-speed operation, like the above low-speedoperation, a response delay of the delivery speed of the extruder 10 tothe conveyor speed of the conveyor belts and the attenuation time areobtained in advance, and the target value of delivery speed of theextruder 10 is set based on the response delay of the extruder 10 andthe attenuation time.

The above high-speed operation is continued until the conveyance of theextruded treads 1 in stock ends (step S17) and then changed to normaloperation, and the operation of the device is suspended when theconveyance of the extruded treads 1 ends (step S18).

Thereby, after return from a trouble, products in stock can be carriedswiftly and the conveying line can be returned to normal operationswiftly.

According to this embodiment, since the buffer means 20Z consisting ofthe expansion conveyor 20 a, inverted conveyor 20 b and expansionconveyor 20 c is interposed between the conveyors 24 and 25 of theconveying unit 20, when a trouble occurs in the receiving unit 30, theexpansion conveyors 20 a and 20 c of the buffer means 20Z are expandedby the expansion control CPU 42 to extend the conveying line, and theextruder revolution R and the conveyor speed V are changed by the speedcontrol CPU 41 to reduce the conveying speed in order to buffer theextruded treads 1 not to carry them to the receiving unit 30. Therefore,the trouble can be solved without carrying the extruded treads 1 to thereceiving unit 30 until the above buffer means 20Z becomes full, and themanufacture of inferior products can be avoided, thereby making itpossible to improve production efficiency.

When the above trouble is solved, the conveying line of the buffer means20Z is made the shortest and the extruder revolution R and the conveyorspeed V are changed to increase the conveying speed and the bufferedextruded treads 1 are carried to the receiving unit 30, thereby makingit possible to carry the extruded treads 1 in stock swiftly. Therefore,the conveying line can be returned to normal operation swiftly.

In the above embodiment, the method of conveying the extruded treads 1has been described. The present invention is not limited to the abovemethod and may be applied to a method of conveying general extrusionmolded products which are continuously delivered from the material feedunit.

The position of the buffer means 20Z is not limited to the positionshown in FIG. 1 and may be between any conveyors out of the conveyors 21to 27, and the buffer means 20Z may have at least one expansionconveyor.

The speed table showing the extruder revolution R and the conveyor speedV of FIG. 3 may be suitably set according to the actual situation of theconveying line.

Industrial Feasibility

As described above, according to the present invention, at least oneexpansion conveyor is interposed between conveyors in the conveying lineof extrusion molded products to be expanded or contracted in order toadjust the conveying speed of the extrusion molded products. Therefore,even when a trouble occurs in the receiving unit, the conveying line isextended by expanding the above expansion conveyor to buffer the aboveextrusion molded products while they are carried. Therefore, it ispossible not to carry the extruded products to the receiving unitwithout suspending the conveying line for a predetermined time. Afterthe trouble is solved, the conveying line is shortened by contractingthe above expansion conveyor to carry the extrusion molded products instock to the receiving unit, thereby making it possible to avoid themanufacture of inferior products and to resume carrying the moldedproducts to the receiving unit swiftly. Consequently, productivity canbe greatly improved.

Since the conveyor speed of the above conveyors can be changed toseveral levels, the conveying speed can be reduced when the troubleoccurs, thereby making it possible to extend the time elapsed before thebuffer becomes full, and the conveying speed can be increased when thetrouble is solved, thereby making it possible to return the conveyingline to a normal state swiftly.

1. A method of conveying extrusion molded products from a material feedunit to a receiving unit by a plurality of conveyors, comprisinginterposing at least one expansion conveyor between conveyors out of theconveyors to expand or contract the expansion conveyor in order toadjust the conveying speed of the extrusion molded products to becarried.
 2. The method of conveying extrusion molded products accordingto claim 1, wherein the conveyor speed of the conveyors can be changedto several levels.
 3. The method of conveying extrusion molded productsaccording to claim 2, wherein the delivery speed of the material feedunit is controlled according to a change in the conveyor speed of theconveyors.
 4. The method of conveying extrusion molded productsaccording to claim 3, wherein when the material feed unit has aplurality of extruders, the speed of each extruder is controlledaccording to a change in the conveyor speed of the conveyors.
 5. Themethod of conveying extrusion molded products according to claim 4,wherein a response delay of the delivery speed of the material feed unitto the conveyor speed of the conveyors and the attenuation time areobtained in advance, and when the conveyor speed of the conveyors ischanged, the target value of the delivery speed is set based on theresponse delay and the attenuation time.
 6. The method of conveyingextrusion molded products according claim 3, wherein the target value ofconveying speed is set according to the throughput of the receivingunit.
 7. A device for conveying extrusion molded products, having aplurality of conveyors to carry extrusion molded products from amaterial feed unit to a receiving unit, wherein at least one expansionconveyor is interposed between conveyors out of the plurality ofconveyors.
 8. The method of conveying extrusion molded productsaccording to claim 4, wherein the target value of conveying speed is setaccording to the throughput of the receiving unit.
 9. The method ofconveying extrusion molded products according to claim 5, wherein thetarget value of conveying speed is set according to the throughput ofthe receiving unit.